As computer-based technologies have evolved, conventional in-person and paper-based transactions, communications, and record-management functions are increasingly performed electronically over networks (e.g., the internet). Increasingly, digital signatures are used in e-commerce and in regulatory filings to implement electronic transactions in a cryptographically protected way. A blockchain is a distributed database or a distributed ledger whose beneficial attributes include permanency and security. These attributes, however, depend on information security techniques implemented using cryptography. Conventionally, to ensure data integrity, the content (such as transactions) of blocks is digitally signed by the content providers, and blocks on a blockchain are hashed by the block publishers. Consumers of information that resides on the blockchain rely on the blockchain hashes and on the digital signatures to verify data authenticity.
Digital signatures are mathematical schemes for demonstrating the authenticity of digital messages or electronic documents. A variety of cryptographic techniques, including symmetric and asymmetric key cryptographic systems, are used to protect data and to create digital signatures. With symmetric key cryptographic systems, a pair of users who desire to exchange data securely use a shared “symmetric” key. With this approach, a sender of a message uses the same key to encrypt the message or create a message authentication code (MAC) that a recipient of the message uses to decrypt the message or verify the MAC. Symmetric key systems require that each of the sender and the recipient establish the shared key in a secure manner. Asymmetric (e.g., public key) cryptographic systems may also be used to exchange messages securely. In public key cryptographic systems, key pairs are conventionally used—public keys and private keys. A sender of a message may encrypt the message using the public key of a recipient. The recipient may use the corresponding private key to decrypt the message.
Additionally, public key cryptographic systems (e.g., asymmetric key cryptographic systems) may be used to produce digital signatures. A sender of a message may sign the message using its private key such that the recipient can knowingly use the sender's public key to verify the digital signature and thus the signed message. A recipient of a message that has been digitally signed can use the public key's owner name and digital signature to verify the identity of the message's sender and to confirm that the message has not been altered during transit. Digital signatures may contain cryptographic hash values calculated over signed content.
The cryptographic landscape is marked by the following developments: deprecation of cryptographic algorithms when they are shown to contain security flaws or weaknesses; the need to extend key lengths over time to maintain confidence in their strength; changes in organizational and/or industry security policy requirements for cryptography; and advances in the state of the art, such as the emergence of new cryptographic algorithms and security techniques offering greater protection or more efficient processing. In the face of continuing changes to the cryptographic landscape, it is desirable to ensure ongoing confidence in digitally signed content, especially if the digitally signed content must be protected over long periods of time. Examples of digitally signed content that must be protected over long periods of time and/or requires long-term storage include 30-year mortgage instruments, title transfer and recordation instruments, long-term contracts, compliance-sensitive transactions, electronic health records and related transactions, and the like.
Although electronic communications have significantly reduced costs and improved efficiencies, they pose significant risks that may impede origin authenticity and data integrity. For example, when blockchain data needs to be verified over a long period of time, such as in an electronically recorded agreement requiring long-term storage (e.g., a 30-year mortgage), encryption techniques used to verify the initial transaction at the time the contract was formed may become outdated. Further, encryption techniques may become compromised. Further still, collaboration among multiple parties that rely on a blockchain may be impeded if these parties cannot agree on a cryptographic method to use to verify content.